Garbage Disposal Humming or Stuck? Troubleshoot, Then Replace

A garbage disposal in a newly purchased property would not work, and the owner of the Everyday Home Repairs channel walked through troubleshooting it in order, from the easiest, no-cost checks up to replacing the unit. The disposal turned out to have a plate rusted through with massive holes.

Check power first

The disposal was plugged into the top outlet. That outlet could be shared with a dishwasher, and the wall switch might control only one of the two outlets, leaving the other powered all the time. With the switch on, a voltage tester confirmed power at the outlet, and the disposal was plugged back in.

The built-in breaker

The disposal has a circuit breaker built in: a small red square sticking out from the bottom. Sticking out means it has tripped, and it must be pushed back in. When power was restored, the motor hummed. The motor was getting power but could not turn. It usually tries for five to ten seconds before the breaker breaks the circuit again, so it doesn't create too much heat.

Turning the motor by hand

A hole in the bottom takes an allen wrench, which may be stored in the sink base, giving a direct line to the motor. It should turn fairly easily, but this one did not. He held the base while turning so as not to rip out the P-trap. Because the property was new to him, he suggested it might not have turned in years.

Looking inside

With the disposal unplugged, he removed the P-trap, using a container for water and gloves for the grime. He also checked for a flexible dishwasher line, which he did not have connected. Rotating the unit released it from the sink drain collar. Looking down, he saw massive holes rusted through the plate. The blades sit on the outside wall, and the plate grinds food toward them. On a healthier disposal, he said, a bone or silverware trapped between the side wall and the internal plate could be the cause, and removing it may fix the problem.

Replacement

About a hundred dollars bought a third horsepower replacement, chosen because it would only handle vegetables. The kit lacks a power cord, which costs 12 to 15 dollars if the old unit is not kept. He installed the elbow with a gasket and a collar held by two bolts. If a dishwasher drains into the disposal, a plug inside must be knocked out.

To swap the cord, he removed the wire nuts, grounding screw and strain relief, and re-stripped the frayed wires. He connected ground first, then black to black and the common, using a pull test on each wire nut, then replaced the access door.

Reinstall and test

The existing sink adapter was in good condition, so he kept it; a new one would need plumber's putty. Three connection points on the adapter must all be engaged. The P-trap compression ring goes with its pointed side down, nut first, snug but not tight until aligned. He ran water to check for drips before plugging in, then flipped the switch with no leaks and a working disposal.